Update HTTP Methods to comply to Fetch Standard

[JulianFrattini]

According to the fetch standard, a http-compliant GET request should not contain a body. However, the API in app.py contains GET endpoints that require a body.

While some clients (e.g., Postman) allow deviation from the fetch standard, other clients (e.g., the fetch library in JavaScript) will cause something like the following error message: TypeError: Window.fetch: HEAD or GET Request cannot have a body. This makes the CiRA functionality unusable as one container within a composition, e.g., as the backend to a web interface.

Consequently, it is suggested to update the HTTP method of all API endpoints that require a body from GET to POST.

[andreas-bauer]

Please have a look at Mozilla's documentation to determine which HTTP method could be used.

• GET: Is Idempotent and Cacheable
• PUT: Is Idempotent but not Cacheable
• POST: Is not Idempotent and Cacheable only if freshness information is included

[JulianFrattini]

According to the classification, the request should be a GET, which is not allowed by the fetch specifications. What method would you recommend?

[JulianFrattini]

Or is it actually a GET method and our approach of requiring a body for the function is wrong?

[andreas-bauer]

My recommendation:

• Use GET with query parameters if the input sentence is simple and does not include any special characters. It is simple and caching would be possible.
• Use PUT if you want to use the body for input and the functions do not have any side effects and therefore are idempotent.
• Use POST if there are side effects.